A review of the Filzer dZ4L bike computer

August 26, 2011

This may be a good bike computer for someone, but it certainly isn't
one for me. My experiences with two units have been negative.

My first dZ4L lasted only a few weeks after I bought it; it failed to
survive a relatively modest Toronto autumn rain. As far as I can see,
this is intrinsic in the design of the computer; the transparent plastic
top seems to be simply pressed very firmly on the main unit, not sealed.
This is basically tailor made for capillary action around the edges, so
once you've got enough water exposure the water starts being drawn up
the sides and into the main display area where it mists up the screen
and then gets into the electronics. Result: dead unit.

After a year of more or less reliable operation out of the rain,
my second dZ4L is now frequently failing to register wheel motion,
resulting in either much too low speed readings or a total glitch. This
appears to be due to the plastic mount warping (and expanding in the
summer heat; hotter weather makes it worse and cooler weather makes it
more reliable) so that it no longer firmly holds the computer against
the mount contacts. It can simply stop working on its own, plus even
small bumps seem quite prone to jarring it just loose enough. Rapping or
pressing the computer into the mount can temporarily make it register
again, but it's far from reliable and rather frustrating. Trying to use
a map case or anything that rests near the mount on the handlebars is
troublesome, because it seems very easy for a velcro strap or whatnot to
put just enough pressure on the computer or the mount to let things come
lose; even a very light touch can be enough.

I find this really unfortunate. The dZ4L's four line display is by
far the best information display of any bike computer that I've seen,
but a bike computer that periodically glitches out and drastically
under-reports speed when I go over even a minor road bump is not a bike
computer, it's an unattractive handlebar ornament.